Abortion, neonatal deaths, and infertility cause important production losses in the livestock industry. Many viral infections are responsible for changes in hematological values of animals. This study aimed to find whether there is any difference in blood parameters of cattle that are naturally infected with BVDV, BHV-1, and BHV-4 and Brucella-seronegative. For this purpose, 401 whole-blood samples collected from cattle were analyzed by ELISA and PCR/RT-PCR to detect specific antibodies and antigens for BVDV, BHV-1, and BHV-4. Hematological analysis and results were compared between naturally infected BVDV, BHV-1, and BHV-4 groups and a control group. Results showed a statistically significant increase in hematological values of group 2 with BVDV compared to the corresponding parameters of group 1 (control) for mean corpuscular volume (MCV), hematocrit (Hct%), mean corpuscular hemoglobin concentration (MCHC), and mean platelet volume (MPV). The same was seen for hematological values of BHV-1 for MCV, Hct (%), and MPV and of BHV-4 for MPV (P < 0.005). However, it was determined that statistical differences in hematological values of naturally infected animals cannot be used as markers for clinical diagnosis of viral infections. Thus, we suggest that evaluations of hematological parameters with specific diagnostic tests are necessary to obtain more reliable results for the diagnosis of viral diseases.